In contemporary telecommunications systems including a power supply, power converters, and electronic circuitry including logic components mounted on circuit boards housed within a frame, it is conventional to provide a grounding system that provides electrical isolation between the power supply, power converters, logic components, and the mounting frames, while ensuring that these isolated units form equipotential ground planes. A truly isolated ground system has equipotential ground planes which are completely isolated from one another except at one dedicated point. The dedicated point is typically formed of a large copper plate referred to as a central office ground (CO GRD) window. If one ground plane is connected to another except at the dedicated point, the grounding system forms a loop path through which current may flow; such a condition is referred to as a ground fault. In general, a greater amount of noise immunity is afforded in a system having ground planes which are electrically isolated from one another except at one common connection point. For example, if noise is introduced into the system's frame, electrical isolation lessens the introduction of the noise into the logic circuitry and other circuitry isolated from the frame. Systems having isolated equipotential ground planes are considered safer than systems without equipotential ground planes as there is no direct current flow between ground planes which are true equipotential planes. It is therefore desirable to have an integrity monitor that will detect the incidence of improperly interconnected ground planes in a telecommunications system.
Accordingly, it is an object of the invention to provide a reliable ground integrity monitor which will detect a ground fault resulting from improperly connected ground planes.